The present invention pertains to a hinge construction, and more particularly to a hinge construction wherein there is employed a concealed electrical component, such as a switch, which can be placed in connection with an electrical circuit to provide an indication as to the opening and closing of a door member with which the hinge is associated.
More specifically, in certain situations, such as building security, building environment control, it is desirable to monitor the building doors, and provide some indication as to their relative positioning, that is, whether the door is ajar, fully closed, or fully opened. Prior to the present invention, hinge constructions were employed wherein a switch or the like was mounted directly to the hinge leaves, note for example U.S. Pat. No. 3,729,603, U.S. Pat. No. 3,715,537 and U.S. Pat. No. 3,803,375. These prior art arrangements, normally utilized a construction wherein a spring biased switch plunger would extend through an aperture formed in one of the leaves, so that the plunger would be depressed when the leaves were in an adjacent or closed condition, but would be allowed to move outwardly as the door was opened. These units, however, are not concealable as is desired in security situations, as the nature or existence thereof can be easily detected when the door is in the open condition.
The present invention provides a novel and practical design for a security hinge, wherein the switch or other component is entirely housed within the hinge knuckles, yet a generally conventional looking hinge is provided. Accordingly, upon assembly of the hinge to a door and door frame arrangement, neither the switch components nor the lead wires are visible, even when the leaves are in a separated or open condition.
As a further matter, the present invention provides a design which enables the sensitivity of the security hinge to be adjusted, and adapted to the desired use. In this regard, at least one of the operating components of the assembly, is adjustably positioned so that before the door has been mounted, the element can be positioned to provide for operation of the switch immediately upon opening, or after a specified degree of opening movement, or only after the door has been fully opened.
While the present invention will be disclosed with regard to a switch, it is envisioned that other electrical components could be employed, such as a variable resistor, the only requirement being that the condition of the component be alterable so that detection of a change of position can be achieved through use of an electrical circuit, to which the component is attached.